Loyola University Chicago Loyola eCommons Master's Theses Theses and Dissertations 1991 Accuracy of an Electronic Apex Locator: A Clinical Evaluation in Maxillary Molar Teeth Jeffrey H. Hembrough Loyola University Chicago Follow this and additional works at: https://ecommons.luc.edu/luc_theses Part of the Oral Biology and Oral Pathology Commons Recommended Citation Hembrough, Jeffrey H., "Accuracy of an Electronic Apex Locator: A Clinical Evaluation in Maxillary Molar Teeth" (1991). Master's Theses. 3722. https://ecommons.luc.edu/luc_theses/3722 This Thesis is brought to you for free and open access by the Theses and Dissertations at Loyola eCommons. It has been accepted for inclusion in Master's Theses by an authorized administrator of Loyola eCommons. For more information, please contact [email protected]. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License. Copyright © 1991 Jeffrey H. Hembrough uaaA.iV lOYOI.A llNiVERSITY MEDICAl CENTEt ACCURACY OF AN ELECTRONIC APEX LOCATOR: A CLINICAL EVALUATION IN MAXILLARY MOLAR TEETH BY JEFFREY H. HEMBROUGH, D.D.S. A Thesis Submitted to the Faculty of the Graduate School of Loyola University of Chicago in Partial Fulfillment of the Requirements for the Degree of Master of Science May 1 991 DEDICATION I dedicate this thesis to the memory of my father, Howard Hembrough, whose life lives on in my mind and serves as a constant example of hard work and dedication. I thank you, Dad, for enabling me to learn and succeed. ii ACKNOWLEDGEMENTS I am indebted to many individuals for their assistance during my studies at Loyola. I would like especially to thank my advisor and mentor, Dr. Franklin Weine, who offered freely his constant guidance, knowledge, and expertise in developing my clinical and.scientific skills. I extend my sincere gratitude to Dr. Jerome Pisano for his insights and assistance which made the completion of this thesis possible. For his assistance in the statistical analysis of the data collected in this investigation, I wish to thank Dr. Donald Doemling. I exress my appreciation to my friends and colleagues, Dr. Salam Sakkal and Dr. Norman Eskoz, for their assistance and moral support throughout this endeavor. My special thanks to my family for their love and encouragement, and especially to my wife, Karen, for her endless efforts throughout my residency. She is a constant source of love, support, and inspiration. iii VITA The author, Dr. Jeffrey H. Hembrough, was born in Jacksonville, Illinois on the fourteenth of December, 1959, the eldest of four sons of Howard and Harriet Hembrough. In August of 1978, he entered Illinois State University in Normal, Illinois where he was··a Dean's List student majoring in Chemistry. He commenced his dental education at Loyola University School of Dentistry in September of 1982, and was graduated cum laude in May of 1986, receiving the degree of Doctor·of Dental Surgery. In July of 1987, he completed a general practice residency with the United States Air Force from which he was honored as a distinguished graduate. In August of 1989, he entered Loyola University School of Dentistry and began a dual course of study leading to the degree of Master of Science in Oral Biology and a Certificate of Specialty Training in Endodontics. iv TABLE OF CONTENTS Page DEDICATION ••.. ii ACKNOWLEDGEMENTS . iii VITA ••••...•. iv TABLE OF CONTENTS V LIST OF TABLES •.. vi LIST OF ILLUSTRATIONS vii Chapter I. INTRODUCTION 1 II. REVIEW OF THE LITERATURE 5 III. MATERIALS AND METHODS • 35 IV. RESULTS •. 49 V. DISCUSSION 63 VI. CONCLUSIONS 79 VII. REFERENCES 87 V LIST OF TABLES Table Page 1 • Summary of electronic apex locator investigations ..••••••.• 33 2. Comparison of techniques for measurement of root canal length: radiographic, electronic, and anatomic . 50 3. Comparison of radiographic and anatomic measurements of root canal length: distobuccal and palatal canals .•••• 53 4. Comparison of electronic and anatomic measurements of root canal length: distobuccal and palatal canals •..• 55 Comparison of radiographic and anatomic measurements of root canal length: distobuccal canal •.••••.••. 58 6. Comparison of electronic and anatomic measurements of root canal length: distobuccal canal . 59 7. Comparison of radiographic and anatomic measurements of root canal lengths: palatal canal . 61 8. Comparison of electronic and anatomic measurements of root canal length: palatal canal •••.•...••.• 62 vi LIST OF ILLUSTRATIONS Figure Page 1. Long-section diagram of root. 8 2. Radiographic misinterpretation of endodontic working length 1 6 3. Rubber dam isolation of the involved tooth 40 4. Radiographic estimation of endodontic working length . 40 5. The Sono-Explorer Mark III electronic apex locator . 42 6. The Sono-Explorer Mark III electronic apex locator . 44 7. Electronic estimation of endodontic working length. • . • . • •• 46 8. Radiographic verification of files in place ••.••••.••••. 46 9. Diagramatic representation of the results 77 1 0. Inaccurate electronic measurements • 81 1 1 • Accurate electronic and radiographic measurement .••••••.••.. 83 1 2. Anatomical obstruction of root apices 85 vii INTRODUCTION The accurate determination of root canal length is a key factor in the success of endodontic therapy. It is widely accepted that canal preparation and filling should be terminated at the cementodentinal junction, which has been defined as the most apical site of the dental pulp (1, 2). The cementodentinal junction generally marks the location of apical root canal constriction and therefore provides a natural area of resistance against which endodontic filling materials may be packed (3). Kuttler (4) found this apical constriction, which he called the minor diameter, to be 0.524 to 0.659 mm from the opening of the apical foramen, known as the major diameter, onto the root surface. Clinical radiographic techniques are employed commonly to determine endodontic working length using the radiographic root apex as a reference point (5). It is recommended by some for endodontic treatment to be terminated 1.0 mm short of this reference. However, the apical foramen has been shown to deviate from the root apex in 50 to 80 percent of the cases, according to studies by Kuttler (4), Coolidge (6), and Hess (7). Pineda and 1 2 Kuttler (8) and Green (9) found these deviations existed 2 to 3 mm from the apical vertex in certain teeth. Such variation can be misinterpreted on two-dimensional dental radiographs. Palmer, Weine, and Healey (10) demonstrated that, in cases where the apical foramen is eccentric to the root apex, radiographic methods are often inaccurate and result in overextension of endodontic preparation and filling procedures. In 1969, Inoue (11) shocked the endodontic community with his presentation at the annual meeting of the American Association of Endodontists in Atlanta by demonstrating that an electronic measuring device could locate the apical constriction. Electronic apex locators provide a physiologic interpretation of a three-dimensional root canal system based on the electrical resistance theory of Suzuki (12) and Sunada (13). They were designed to reduce the subjectivity involved in radiographic interpretation and to decrease the potential for a high number of radiographs often needed in endodontic treatment. The accuracy of electronic apex locators has been clinically evaluated in several studies, with conflicting results. In 1975, Seidberg et al. (14) determined digital-tactile sense confirmed by radiographs to be superior to the Sono-Explorer electronic apex locator in the estimation of root canal length. Similarly, in 1980, Becker et al. (15) 3 found radiographic determination to be more accurate than that of an electronic measuring device when compared to the direct anatomical lengths of 24 extracted teeth. conversely, in 1976, Busch et al. (16) reported the Sona-Explorer to be within 0.5 mm of the radiographic apex in 93.3 percent of the 72 single-rooted teeth studied. Plant and Newmann (17), also in 1976, found the Sano-Explorer to be superior to radiographic length determination in an investigation which made direct anatomical measurements of root canal length following tooth extraction. At present, results are inconclusive as to the ability of electronic apex locators to determine accurately root canal length in a clinical environment. In contrast to previous studies, this investigation will focus solely on maxillary first and second molar teeth. Because of the multiple anatomic structures which overlap radiographs of maxillary molars, such as the malar process of the maxilla and the floor of the maxillary sinus, these teeth are the most difficult to interpret during endodontic therapy. Film placement and patient cooperation while radiographing these teeth may be problematic as well. In combination, these factors can make radiographic determination of root canal length in maxillary molar teeth less than ideal. Therefore, the ultimate success of endodontic therapy may be jeopardized in such instances. 4 No other study has specifically involved the maxillary molars, though Bramante and Berbert (5) included 22 maxillary molars in an investigation comprised of 224 teeth. Based upon the contradictory conclusions of previous investigations and a lack of data concerning the maxillary molar teeth, this thesis will evaluate the clinical accuracy of an electronic apex locator, the Sona-Explorer Mark III, in the determination of root canal length in the distobuccal and palatal canals of maxillary